diff --git a/src/platform/plugins/shared/data/common/search/expressions/esql.test.ts b/src/platform/plugins/shared/data/common/search/expressions/esql.test.ts
new file mode 100644
index 0000000000000..8bdf796dc575e
--- /dev/null
+++ b/src/platform/plugins/shared/data/common/search/expressions/esql.test.ts
@@ -0,0 +1,51 @@
+/*
+ * Copyright Elasticsearch B.V. and/or licensed to Elasticsearch B.V. under one
+ * or more contributor license agreements. Licensed under the "Elastic License
+ * 2.0", the "GNU Affero General Public License v3.0 only", and the "Server Side
+ * Public License v 1"; you may not use this file except in compliance with, at
+ * your election, the "Elastic License 2.0", the "GNU Affero General Public
+ * License v3.0 only", or the "Server Side Public License, v 1".
+ */
+
+import { of } from 'rxjs';
+import { UiSettingsCommon } from '@kbn/data-views-plugin/common';
+import { getEsqlFn } from './esql';
+import { ExecutionContext } from '@kbn/expressions-plugin/common';
+import { ESQLSearchResponse } from '@kbn/es-types';
+import { IKibanaSearchResponse } from '@kbn/search-types';
+
+describe('getEsqlFn', () => {
+  it('should always return a fully serializable table', async () => {
+    const mockSearch = jest.fn().mockReturnValue(
+      of({
+        rawResponse: {
+          values: [['value1']],
+          columns: [{ name: 'column1', type: 'string' }],
+        },
+      } as IKibanaSearchResponse<ESQLSearchResponse>)
+    );
+
+    const esqlFn = getEsqlFn({
+      getStartDependencies: async () => ({
+        search: mockSearch,
+        uiSettings: {} as UiSettingsCommon,
+      }),
+    });
+
+    const input = null; // Mock input
+    const args = {
+      query: 'SELECT * FROM index',
+    };
+
+    const context = {
+      abortSignal: new AbortController().signal,
+      inspectorAdapters: {},
+      getKibanaRequest: jest.fn(),
+    } as unknown as ExecutionContext;
+
+    const result = await esqlFn.fn(input, args, context).toPromise();
+
+    expect(result?.type).toEqual('datatable');
+    expect(() => JSON.stringify(result)).not.toThrow();
+  });
+});
diff --git a/src/platform/plugins/shared/data/common/search/expressions/esql.ts b/src/platform/plugins/shared/data/common/search/expressions/esql.ts
index b2c6c15ad2426..327641e460af1 100644
--- a/src/platform/plugins/shared/data/common/search/expressions/esql.ts
+++ b/src/platform/plugins/shared/data/common/search/expressions/esql.ts
@@ -345,8 +345,8 @@ export const getEsqlFn = ({ getStartDependencies }: EsqlFnArguments) => {
 
           const appliedTimeRange = input?.timeRange
             ? {
-                from: DateMath.parse(input.timeRange.from),
-                to: DateMath.parse(input.timeRange.to, { roundUp: true }),
+                from: DateMath.parse(input.timeRange.from)?.toISOString(),
+                to: DateMath.parse(input.timeRange.to, { roundUp: true })?.toISOString(),
               }
             : undefined;